[Coco] (Marginally Topical) TRS-80 Model I Troubleshooting

[Joel Ewy]

On 08/15/2013 09:13 PM, Chris Dent wrote:
>> But if I power it up with the expansion unit switched on I get garbage on the screen
>
>
> When a Model I is connect to an expansion interface the first thing it tries to do is load and
>
> execute the boot sector from the floppy.  If it fails to boot, it doesn't fall back to the BASIC
>
> Interpreter, it just hangs.
>
> Hold the BREAK key down when powering up and that should get you into BASIC

Ooh, hey, if I ever knew this once back in the day I've forgotten it.  
When I was in 6th grade I read a book on BASIC for the TRS-80 Model I, 
but by the time I'd convinced my parents to get me a computer the Model 
I was discontinued, and that's how I got into the CoCo.  So it's 
possible that I had read that once upon a time, but not having used it, 
it sure didn't stick with me.  When I get some time to play with it 
again I'll try that before I go trying to clean the contacts or re-seat 
the chips.  Thanks for the tip, Chris.

JCE

>
>
>
>   _____ _          _     | Chris Dent
>
> /  __ \ |        (_)    | Flinders University
>
> | /  \/ |__  _ __ _ ___ | +61-8-8204-5461
>
> | |   | '_ \| '__| / __|| chris.dent at flinders.edu.au
>
> | \__/\ | | | |  | \__ \|
>
>   \____/_| |_|_|  |_|___/|
>
> If you mod me down, I will become more insightful than you can possibly imagine
>
>
>
> -----Original Message-----
> From: coco-bounces at maltedmedia.com [mailto:coco-bounces at maltedmedia.com] On Behalf Of Joel Ewy
> Sent: Monday, 5 August 2013 1:09 PM
> To: CoCo-MaltedList
> Subject: [Coco] (Marginally Topical) TRS-80 Model I Troubleshooting
>
>
>
> So I was given a TRS-80 Model I system on Friday.  It includes the TRS-80, an Expansion unit, a monitor, a very, very strange "screen printer", a pair of floppy drives, a broken but physically very nice CTR-80, a bunch of of programs on cassette (including a boxed Avalon Hill Planet Miners game), and a box labeled "TRS-80 floppy disks" that appear from the labels on the individual disks themselves to actually be Apple 2 disks, though I don't yet know what is on them.
>
>
>
> The computer powers on.  The monitor works but has an extremely touchy vertical hold.  But if I power it up with the expansion unit switched on I get garbage on the screen.
>
>
>
> Next time I have the time to clear the space to set it up and play with it, I'll try cleaning the card edge contacts between the TRS-80 and the expansion unit, as I gather this is a common failure.  But if that doesn't work, is there any other wisdom about likely problems with the Expansion unit?  Reseat socketed chips?  Check for bad caps?
>
>
>
> What about the vertical hold on the monitor?  I'm not afraid of a soldering iron, can read a schematic, know what not to touch inside a TV, and where to keep my other hand, but don't have a good enough grasp of CRT circuits to really know where to find the V. hold parts or know what to suspect.  (I do have an ancient copy of TAB's "101 TV Troubles and How to Fix Them" or some such.  But it predates even the TRS-80 monitor by a few years.)
>
>
>
> Thoughts?  Suggestions?
>
>
>
> JCE
>
>
>
>
>
> --
>
> Coco mailing list
>
> Coco at maltedmedia.com<mailto:Coco at maltedmedia.com>
>
> http://five.pairlist.net/mailman/listinfo/coco
>
>
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
>